Large asteroid safely zips past Earth, dragging its moon along

All about asteroids – This graphic shows the track for asteroid 2004 BL86, which flew about 745,000 miles from Earth on Monday, January 26. That's about three times as far away as the moon.

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This graphic shows the path Asteroid 2014 RC took as it passed Earth on September 7. The space rock came within one-tenth the distance from Earth to the moon.

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NASA scientists used Earth-based radar to produce these sharp views of the asteroid designated "2014 HQ124" on June 8. NASA called the images "most detailed radar images of a near-Earth asteroid ever obtained."

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The Hubble Space Telescope snapped a series of images on September 10, 2013, revealing a never-before-seen sight: An asteroid that appeared to have six comet-like tails.

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A diagram shows the orbit of an asteroid named 2013 TV135 (in blue), which made headlines in September 2013 when it passed close by Earth. The probability of it striking Earth one day stands at 1 in 63,000, and even those odds are fading fast as scientists find out more about the asteroid. It will most likely swing past our planet again in 2032, according to NASA.

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Asteroid 2012 DA14 made a record-close pass -- 17,100 miles -- by Earth on February 15, 2013. Most asteroids are made of rocks, but some are metal. They orbit mostly between Jupiter and Mars in the main asteroid belt. Scientists estimate there are tens of thousands of asteroids and when they get close to our planet, they are called near-Earth objects.

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Another asteroid, Apophis, got a lot of attention from space scientists and the media when initial calculations indicated a small chance it could hit Earth in 2029 or 2036. NASA scientists have since ruled out an impact, but on April 13, 2029, Apophis, which is about the size of 3½ football fields, will make a close visit -- flying about 19,400 miles (31,300 kilometers) above Earth's surface. The images above were taken by the European Space Agency's Herschel Space Observatory in January 2013.

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If you really want to know about asteroids, you need to see one up close. NASA did just that. A spacecraft called NEAR-Shoemaker, named in honor of planetary scientist Gene Shoemaker, was the first probe to touch down on an asteroid, landing on the asteroid Eros on February 12, 2001. This image was taken on February 14, 2000, just after the probe began orbiting Eros.

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The first asteroid to be identified, 1 Ceres, was discovered January 1, 1801, by Giuseppe Piazzi in Palermo, Sicily. But is Ceres just another asteroid? Observations by NASA's Hubble Space Telescope show that Ceres has a lot in common with planets like Earth. It's almost round and it may have a lot of pure water ice beneath its surface. Ceres is about 606 by 565 miles (975 by 909 kilometers) in size and scientists say it may be more accurate to call it a mini-planet. NASA's Dawn spacecraft is on its way to Ceres to investigate. The spacecraft is 35 million miles (57 million kilometers) from Ceres and 179 million miles (288 million kilometers) from Earth. The photo on the left was taken by Keck Observatory, Mauna Kea, Hawaii. The image on the right was taken by the Hubble Space Telescope.

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One big space rock got upgraded recently. This image of Vesta was taken by the Dawn spacecraft, which is on its way to Ceres. In 2012, scientists said data from the spacecraft show Vesta is more like a planet than an asteroid and so Vesta is now considered a protoplanet.

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The three-mile long (4.8-kilometer) asteroid Toutatis flew about 4.3 million miles (6.9 million kilometers) from Earth on December 12, 2012. NASA scientists used radar images to make a short movie.

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Asteroids have hit Earth many times. It's hard to get an exact count because erosion has wiped away much of the evidence. The mile-wide Meteor Crater in Arizona, seen above, was created by a small asteroid that hit about 50,000 years ago, NASA says. Other famous impact craters on Earth include Manicouagan in Quebec, Canada; Sudbury in Ontario, Canada; Ries Crater in Germany, and Chicxulub on the Yucatan coast in Mexico.

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NASA scientists say the impact of an asteroid or comet several hundred million years ago created the Aorounga crater in the Sahara Desert of northern Chad. The crater has a diameter of about 10.5 miles (17 kilometers). This image was taken by the Space Shuttle Endeavour in 1994.

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In 1908 in Tunguska, Siberia, scientists theorize an asteroid flattened about 750 square miles (1,200 square kilometers) of forest in and around the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia.

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What else is up there? Is anyone watching? NASA's Near-Earth Object Program is trying to track down all asteroids and comets that could threaten Earth. NASA says 9,672 near-Earth objects have been discovered as of February 5, 2013. Of these, 1,374 have been classified as Potentially Hazardous Asteroids, or objects that could one day threaten Earth.

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One of the top asteroid-tracking scientists is Don Yeomans at the Jet Propulsion Laboratory, which is managed by the California Institute of Technology. Yeomans says every day, "Earth is pummeled by more than 100 tons of material that spewed off asteroids and comets." Fortunately, most of the asteroid trash is tiny and it burns up when it hits the atmosphere, creating meteors, or shooting stars. Yeomans says it's very rare for big chunks of space litter to hit Earth's surface. Those chunks are called meteorites.

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Asteroids and comets are popular fodder for Earth-ending science fiction movies. Two of the biggest blockbusters came out in 1998: "Deep Impact" and "Armageddon." (Walt Disney Studios) Others include "Meteorites!" (1998), "Doomsday Rock" (1997), "Asteroid" (1997), "Meteor" (1979), and "A Fire in the Sky" (1978). Can you name others?

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Asteroid 1998 QE2 is about 3.75 million miles from Earth. The white dot is the moon, or satellite, orbiting the asteroid.

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Story highlights

Asteroid 1998 QE2 will next pass the Earth in 2028

Scientist have been anticipating the asteroid's passing for a few years

Images of it should compare well to those shot by spacecraft, NASA says

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Scientists have been rubbing their hands for a decade and a half for this opportunity since they discovered the asteroid on August 19, 1998, the year for which it is named. The letter "Q" stands for the month of August.

"As my old friend, radar astronomer Steve Ostro used to say, spaceship Earth is making a fly-by of the asteroid, so we're going to exploit the capabilities of the radars to understand as much as possible," Benner said, according to a story on NASA's website.

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A milestone asteroid

1998 QE2 represents a milestone in NASA's Near Earth Object Project, which scopes out the heavens for potential danger from celestial projectiles whizzing past.

"It's one of the initial successes of our effort to find the big asteroids that could hit the Earth and cause global catastrophe," said Paul Chodas, a scientist with the project. "It's certainly one to keep an eye on."

The discovery of its moon -- which makes it what scientists call a binary asteroid -- surprised the astronomers, said NASA radar scientist Marina Brozovic, who helped take the images at Deep Space Network antenna at Goldstone, California.

More than 15% of asteroids travel in groups of two or three objects revolving around one another, according to NASA.

Destructive potential

1998 QE2's moon, which is 2,000 feet wide, is large enough for NASA to term it a "potential city killer." The asteroid it revolves around is much bigger, at 1.7 miles wide.

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Any asteroid as large as a half-mile across would cause a global catastrophe, if it struck the blue planet, he added.

To put the potential for damage by an asteroid into perspective, the one that paleontologists believe triggered the extinction of dinosaurs on Earth 65 million years ago was six miles in diameter.

The meteor that exploded over Russia in February, injuring more than 1,000 people and causing millions of dollars in damage, was a "very small asteroid," according to the space agency.

The most dangerous asteroids contain a lot of stone or iron, according to NASA. 1998 QE2 contains a good bit of carbon and well as amino acids, the building blocks of protein.

The NEOP has identified 95% of asteroids of this most dangerous order, Chodas said. Luckily, there is no known possibility of one slamming into the planet.

But NASA has not yet done much work on the meteors one class lower, known as the "potential city killers." They start at a size of 150 yards in diameter. NASA astronomers have identified only 10% of the 10,000 they believe pass close to Earth.

NASA officials this year told a congressional panel, which was considering future defense systems to prevent a potential asteroid strike, that there is only a one in 20,000 chance that a truly dangerous one will hit Earth in a year's time.

Having a look

Even as it jets further and further away, astronomers will continue making images of 1998 QE2 through June 9 with two radar antennas -- one in California and a second one in Puerto Rico.

NASA takes threats from asteroids seriously, and will keep calculating the orbits of the large ones they identify long to check their flight paths for any potential danger to Earth.

Eventually, 1998 QE2 will curve back out toward the solar system's outer asteroid belt, which is just short of Jupiter.

It will go by Earth next on July 12, 2028, according to NASA's Jet Propulsion Laboratory. But that time there will be lots more elbow space -- the asteroid is expected to be about 45 million miles away.

There will be a much closer call comes in about 200 years. Even then, though, scientists believe history will repeat itself -- and our planet will once again survive.